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Advantages of very early sowing of wheat in WA

A. Heinrich

Avon Districts Agricultural Centre, Northam WA 6401

Adoption of 'new' semi-dwarf varieties of wheat by WA wheat farmers has been relatively slow. The importance of improved management techniques to maximise the potential yield of these new varieties, in particular, time of sowing has been clearly shown (1). Significant yield penalties of up to 50 kg/ha/day delay in sowing have been recorded in the central wheat belt. This work describes the yield response to time of sowing by late, medium and early maturing varieties of wheat in the central wheat belt of WA.


Nine varieties of wheat were sown at Dowerin (3110's, 11712'E) on a grey brown loamy sand (0-25 cm) over gravelly yellow clayey sand (25 cm+) on 25 April, 17 May and 8 June 1989. The site received 274 mm April to October rainfall. In this paper the yields of three varieties only, Spear, Aroona and Kulin, representing late (+8 days to anthesis compared to Aroona), medium (0 days) and early (-4 days) maturity varieties, respectively, will be discussed. Weeds were controlled with pre- and post-emergent herbicides as required.

Results and discussion

The grain yield of Spear decreased from 4.2 t/ha when sown on 25 April to 2.9 t/ha from the 8 June sowing date. By contrast, the grain yield of Aroona increased from 3.0 t/ha from the earliest sowing to 3.5 t/ha from the 17 May sowing date and declined to 2.9 t/ha at the late sowing. The yield of Kulin increased with delayed sowing from 2.6 t/ha from the 25 April sowing to a maximum of 3.4 t/ha from the 8 June sowing. The yields of these varieties reflect their maturity types and the resulting interaction between anthesis dates and sowing dates. Kulin reached anthesis six to eight days before Aroona and 14 to 17 days before Spear at each time of sowing, with Kulin flowering 10 days before the optimum flowering period (7 to 27 September) when sown on 25 April. By contrast, Spear flowered within the optimum flowering period when sown on 25 April. The reverse occurred wit the 8 June sowing where Kulin flowered within the optimum period and Spear flowered late. Aroona, the medium variety flowered seven days prior to the optimum period when sown on 25 April and within the optimum flowering period from the 17 May and 8 June sowings.

Maximum yield, over all varieties, was achieved with Spear sown on 15 April. Delayed sowing restricted the potential yield of Spear at this site, with a yield penalty of 50 kg/ha/day. This contrasts with Aroona and Kulin, where early sowing restricted their potential yield. Late maturing varieties are suited to early sowing, whereas shorter maturity types are suited to later sowing dates, as their development patterns allow them to flower after the risk of damaging frosts has past, and before spring drought restricts grain filling, and hence yield. Therefore to maximise the potential yield of a site in WA, where the growing season is short and moisture stress develops rapidly, very early sowing and the selection of a variety with appropriate maturity type for a given time of sowing is important.


Funding for this work from the Grains Research and Development Corporation is gratefully acknowledged.


Anderson, W.R. In: Management and Agronomy of High Yielding Wheat Varieties.

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